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Fjords Contribute to Melting of Glaciers

Greenland’s glaciers are melting faster than they used to, contributing to the rise of sea levels worldwide. While warmer atmospheric temperatures thin all the glaciers from above, scientists have wondered if warmer waters are also melting the many glaciers that flow into the fjords.

Two studies published in Nature Geoscience provide evidence that this is the case.

In one study, Fiammetta Straneo of the Woods Hole Oceanographic Institution and colleagues looked at water temperatures and circulation in a fjord in East Greenland that is the terminus of Helheim glacier. They found that the 3,000-foot-deep fjord was continually being replenished with relatively warm (that is to say, 38 to 40 degrees Fahrenheit) water from the sea shelf beyond, driven by winds.

Photo

Fjords in Greenland are playing a role in changing the region’s glaciers.Credit
Michael Kappeler/Agence France-Presse — Getty Images

They suggest that this warmer water is causing increased undersea melting of the glacier at its terminus and that the same phenomenon could be occurring at other glaciers as well. Atmospheric and oceanic changes are responsible, they say, because they have altered the properties of the shelf water and the wind patterns to cause more and warmer water to enter the fjord.

The second study, by Eric Rignot of the University of California, Irvine, and the Jet Propulsion Laboratory and colleagues, looked at the rates of undersea melting at four glaciers in West Greenland. This isn’t easy to do: it involves measuring water velocity, temperature and salinity near the glacier front to determine the patterns of mixing and flow, and then calculating melting rates.

The researchers say that cold melt water from underneath the glacier combines with rising warmer, saltier water from the depths of the fjord. This rises along the underwater face of the glacier, melting it. The mixed waters then flow out into the glacier in a plume. They calculated the rates of undersea melting to be up to two orders of magnitude larger than surface melting rates.

Taken together, the two studies suggest that fjords play an important role in the changes taking place in Greenland’s glaciers.

A version of this article appears in print on February 16, 2010, on Page D3 of the New York edition with the headline: Fjords Contribute To Melting of Glaciers. Order Reprints|Today's Paper|Subscribe